Thanks, guys. After decades of nitro, I cut my teeth on a DLE 31, and learned pretty quick, not to deviate from break in, and never go with synthetic oil or drop oil mix until you're convinced its well broken in. Also understanding that tuning on the ground will not be the same in the air, and with/without cowl will also change tune. Since then, I've grown both confident, comfortable, and competent in gas operation.

I've seen the Saito, and its a piece of art. I'll bet it sounds amazing being a 4 stroke. That would certainly be new territory for me, and I don't think I'm ready to go with new-to-me-tech on a twin.

That KMP looks great! and those 20's fit well. Since no one appears to have shared their experience or done a really small gasser, I guess I'll be pioneering it. Unless someone chimes in!? I think I saw an older post that said, that a 20 will overheat because there wouldn't be sufficient airflow. I think I'll wait for the plane to arrive, take some firewall/cowl measurements and compare to engine size/weights and go with what will fit. Oh and account for weight as well. It appears the electric guys have to be creative with getting batteries right up behind and under their motors, then still add nose weight. I hope to avoid that with proper planning. Really like to be under 18lbs dry.
I keep flashing back to the mid 80s and my beloved Duelist. Had it for 2 seasons, until a flameout on landing cartwheeled it... all that stiff crappy Pica balsa exploded!!! I'd mention I'm also the proud owner of an actual Duelist 2/60 kit that was kitted many years ago. I think there were only about 100 done? Good balsa. Someday I'll build that sucker.

I found a post from a fella who is flying VVRC 21cc's in his VQ-38: https://www.rcgroups.com/forums/show...3-P-38/page234 Unfortunately, he hasn't posted much more than pictures and a video. It appears he got the engines in without hacking up the cowl, and his weight is under 20lbs. I'm encouraged.

Update. So I popped for the VVRC 21cc counter-rotating gas engine pair. They are roughly the size of an .80 to .90 4-stroke, and are similar in weight, minus the ignition and ignition battery. Oh, and turns out, the cylinders can be rotated 180 degrees so muffler placement can be a choice-- as long as one rotates the piston as well. That way, porting remains as intended (confirmed by Tom at Valley View RC). I intend to configure the engines so the props rotate from outboard to inboard. Not scale, but will help should an engine flame out during flight. Also debating the install of an Eagle Tree Guardian gyro to buy me a wee bit of time should I get a flame out. I've read a few reports that having a gyro permitted the pilot to at least get their bird down in one piece. Just wish I knew how to set up the Guardian to compliment the VQ-38.

@jbbodz: You'll enjoy building the Guillows-38. I did one years ago. I considered a couple of OS .10s, but I never managed to finish it out with engines. The Guillows-38 is very light, and not really designed for RC without adequate bracing (consider sheeting the entire bird in balsa. While the Cox 049s might be an obvious choice, you'll want for a throttle, and I've never been impressed with Cox's attempt to add throttles to their design. There are some other options here in the US if you're interested. Brodak MK II .049 RC Engine
Then there is HobbyKing: https://hobbyking.com/en_us/ap-061a.html

There are several electric builds here and the other big RC forum, and I have to say, I would go electric with this one. You loose an engine or run your tank dry in a engine, and it will roll and stall into Terra Firma so fast, recovery is HIGHLY unlikely. In some builds, electric retracts were even used with electric power.

Thanks for advise on that, much appreciated. I haven't had anything to do with the Brodak engines. Are they any good? Just did a little looking on the net before. I have had an AP 061, in a sea plane, which successfully pulled the plane off the water. So I regard it as a fairly powerful engine. I don't think the cox 049 has much punch however a nice common engine for parts.

I've heard good things about the AP 061. I have an 09 I got from Hobbyking, but they don't seem to stock it anymore. If you go nitro, the 061 might be your best bet, if you can get them both tuned for reliable running. John Brodak is arguably the savior of control line modeling here in the US. Being such a small niche hobby, he is the last full service retailer dedicated to all things control line. He's been in business for many many years and sells only quality products. His prices may seem a little high, but they really aren't because no one else has been able to keep a dedicated control line business successful. So his margins are necessary so he can stay in business and support those products. And he also stands behind his products. He carries "R/C" versions of some engines because those are used in some 3-line events where throttle is necessary, like "carrier landing" and such. 3rd line is handled by a trigger in the handle. I buy from him with no reservations whatsoever.

Thanks for that. I can appreciate that. Need to support local business to stay a float. Do that here in NZ as much as I can. The AP061 i have runs well. However it is the only chinese engine i have, because of its origin i guess it will never be anything special just a cheap motor that one hopes lasts. I figure there will be a failure elsewhere before its service life is up anyway haha. The norvel 061 would be good as hat is the genuine article.

My impressions are that the engines Brodak sells are decent, he doesn't sell junk. The Norvel .061 Mig Mig is a very powerful engine, a touch more than the Tee Dee .049 given its Schneurle porting and increased displacement. Haven't heard anything really negative about the AP 061. It is basically a copy of the earlier Norvel. Last checked, both the AP 061 and 09 are available at Hobby King Hong Kong site, only AP 15 (actually a .14) is available in US warehouse.

I put a non-throttle venturi version on an Airtronics 36" Q-Tee, no longer did it fly trainer like, became a fun sport flier. This was even detuned through a Mecoa glow plug head adapter that dropped compression. Q-Tee has 250 sq. in. wing area. Proportioning real P-38 52 ft span 327 sq. ft. wing area to Guillow P-38 40" span come up with 193 sq. in. wing area.

Having built many Guillow kits, P-38 is framed in standard Guillow fashion ala rubber power framing, which is not stressed for RC power flight. I concur with the comment to sheet in the structure in strategic areas to add strength. Because of the light framing and the power of the .061, seems like an overkill to use two. A throttled single in the nose IMO would be a better choice, although would detract from scale appearance on the ground.

Reason why I say this, is that the P-38 is reasonably clean aerodynamically. Back in 1974, there was a 44" span Tee Dee .049 powered 2 channel pattern plane by Owen Kampen called the "Pacer" that was also kitted by Ace R/C, https://outerzone.co.uk/plan_details.asp?ID=7186. The single Tee Dee was sufficient power for 2 channel aerobatics.

Appreciate all the useful input thanks for all the help. Do you think the wing area is lcking a bit on the p38? This is what i had gathered from reading on the net. Would almost benefit from a larger wing area i think. I think either way it will still fly however perhaps like a brick needing some speed to keep it up. Ideally would like to keep two engines for the scale look. Yes some reinforcing would be necessary